Part of the problem that happens in schools all over the English-speaking world is that the English language is perceived to be the domain of the English teacher. It shouldn't be. So, for example, perhaps the math teacher doesn't correct mistakes in spelling or sentence structures, diction or grammar, etc. Kids usually have about one class (of eight or so classes per day) of English. Subsequently, many things slide.

Another difficulty is thr ready convenience of garbage grammar checks and less than enviable spell checks; the easy type of writing that occurs on chats like MSN 'if u no what I mean'. There seems to have been a general lowering of standards. The solution? I wish I knew.